What is Legionnaires’ disease?

Legionnaires’ disease is a rare form of pneumonia. It was named after an outbreak among a meeting of the American Legion in 1976. Legionnaires’ disease is caused by legionella bacteria. The bacteria are commonly found in stagnant water in ponds, pipes and water-cooling systems. The hazard occurs when the bacteria are contained within water droplets which are dispersed and inhaled. Cases of Legionnaires’ disease are rare. In 2017 there were 693 cases in England and Wales reported to Public Health England.

Who is susceptible?

Not everyone is equally susceptible to the infection. Those with the greatest risk appear to be smokers and people with underlying poor health issues, in particular, respiratory tract problems. Heavy drinkers are also more susceptible. Men are at greater risk than women by a ratio of 3:1 and it usually affects the middle-aged or elderly; the disease is uncommon in younger people and very rarely affects those under the age of 20.

Symptoms and treatment

Initial symptoms are high fever, headache, chills and muscle pain. Some patients then develop pneumonia, diarrhoea and delirium. The incubation period is from two to ten days. There is no evidence of person-to-person spread.

Because the symptoms are similar to those of flu, it is not always easy to diagnose. A blood or urine test will establish the presence of the disease.

The illness is treated with antibiotics.

Legionnaires’ Disease and schools

All workplaces, including schools require a risk assessment. Schools tend not to have complex air conditioning systems that involve the use of cooling systems which have been the source of major legionella outbreaks in the past. However, schools may have fixtures such as drinking fountains, showers and spa baths which may give rise to sprays or aerosols containing legionella bacteria and it is here where the major risk lies.

Employers should have in place a risk assessment, appropriate measures for dealing with any problems highlighted and a system for recording the application of those measures, with a log book available for inspection. The risk assessment should be reviewed annually, and more frequently following any changes to water systems and following any failure in control measures.

Particular hazards are:

  • old and unused or infrequently used showers
  • water features
  • machine tool coolant systems
  • spa baths
  • hose reel and sprinkler systems
  • poorly maintained ageing hot and cold water systems
  • roof tanks
  • hidden unused pipework
  • emergency eyewashes.

The detection of legionella bacteria in a school water system does not represent an immediate hazard if there is no chance of the bacteria getting out. Provided the bacteria remain isolated in the pipework, and prompt and adequate efforts are made to deal with the problem, there should be no cause for major concern.

Small electrically operated air conditioning systems frequently used in school IT suites should not be a hazard.

For more information, please download the full ‘Legionnaires' disease in schools’ guidance